ki84 speed????

[Karnak]

Pyro,

Do you have any idea why the British rated the Ki-84's roll rate 25% higher than the Seafire's and why they said that it didn't suffer from control heaviness at higher speeds as much as other Japanese fighters?

It seems nearly as bad as the the A6M series on both counts right now.

[busa]

Thank you for Kweassa which made wonderful translation.

to Mitsu and all.

[oboe]

Thanks for clearing that up Pyro.   FWIW I view the sluggish rollrate of the Ki.84 as a more serious problem than 388 vs 392 mph top speed.

With regard to busa's posting it does seem like rollrate is an issue to be looked at.

Has anyone compared AH's Seafire rollrate to the Ki.84 rollrate?

EDIT:   I just completed some offline testing comparing the Seafire's rollrate to the Ki.84s.   Starting each A/C with 50% fuel, all tests were done at 5,000' AGL, IAS of 250 mph.   I did one complete barrel roll 3 times each, left and right and took an average for each direction.   Interesting results:

The Seafire rolled left about 94 deg/sec, and rolled right at 98 deg/sec.

The Hayate rolled left at 76.5 deg/sec and rolled right at 77.6 deg/sec.

So the AH Ki.84 has a significantly worse rollrate than the AH Seafire, not 25% better as Wotan's post above indicated RL Royal Navy testing revealed.

[Pyro]

I agree that the roll rate is unrealistically low with what's been presented.

[Karnak]

Pyro,

Does the elevator heaviness look correct to you?

Thanks for looking at the roll rate.

[2bighorn]

Originally posted by Pyro
I agree that the roll rate is unrealistically low with what's been presented.

Cool, that means it'll be fixed

Question... Why wasn't Ki-84 modelled with Homare 21 engine? N1K2 has the same engine and most of data you already have (WEP, etc).

That way you'd have less guessing, plus you would get "real" late war Frank, which was competitive against P51s, P47s and P38s.

One more... Any plans of adding K-84 with Homare 21 (or even 23) in the future? Or perhaps Ki-84-Ib?


EDIT:
Can you check the dive speeds as well? Ki-84 was succesfully brought to 496mph in dive with no ill effects, in AH2 it sheds ailerons and elevators somewhere between 490-500mph.

Could there be transission period of about 20-30mph before parts start falling off like most other AH planes have?

[Grits]

I also feel the poor roll rate is a bigger liability than the top speed. Good to know  you are looking into it Pyro. Even if it was increased to somewhere near the Seafire, not necessarily above it, in roll rate that will go a long way to making it a more competitive ride.

I think we should let the dust settle, let Pyro and HT work out the kinks in the Ki84, and in the end we will have a plane just about everyone can live with.

[Karnak]

Originally posted by Grits
I think we should let the dust settle, let Pyro and HT work out the kinks in the Ki84, and in the end we will have a plane just about everyone can live with.

Well, once the roll rate is increased it'll be a lot better.

I'm still a bit unhappy about the elevator heaviness at speed.

Durability seems very low, more like what I'd expect of a Ki-43, minus the fires.  I have yet to be hit without losing major parts of the aircraft.  It seems more fragile than the A6M2 or Spitfire Mk I and based on it's weight that seems odd.

[GRUNHERZ]

Originally posted by Pyro
Going back to the speed issue.  The speed as modeled is the official performance taken from a translated Ki-84 manual.  Now I think the point of confusion over the official specs is because of the fact that the top speed was 624 kph, which happens to be the same top speed that is cited in the test of a prototype.  So the assumption was that the official performance was simply the results of the early prototype test and that production numbers should be higher because of improvements such as better exhaust stacks and perhaps some aerodynamic refinements.  However, this theory fell apart when Busa's research found that the prototype's top speed of 624 kph was reached using +350mm/3000 RPM.  The 624 kph in the official performance was reached using +250mm/2900 RPM, the military power limit used in production Ki-84s.  So in fact, this does show that some improvements were made as the production version reached the same speed as the prototype at a lower power setting.  It's just that the production models were derated to the lower setting, so the improvements were not seen in the top speed figure.

Pyro thanks for the insight into your decision process to model Ki84 at 324/388.

[StarOfAfrica2]

Originally posted by Karnak
Well, once the roll rate is increased it'll be a lot better.

I'm still a bit unhappy about the elevator heaviness at speed.

Durability seems very low, more like what I'd expect of a Ki-43, minus the fires.  I have yet to be hit without losing major parts of the aircraft.  It seems more fragile than the A6M2 or Spitfire Mk I and based on it's weight that seems odd.

Doesnt seem that bad in the durability dept. to me.  Of course experiences will vary and most of my encounters thus far have not been vs anything with cannons.  It takes quite a pounding from buff gunners without coming apart though.  I landed two times last night after going up against B24 formations, both times I lost the engine and still managed to hang in a glide behind them long enough to get kills.  VERY stable gun platform, even fishtailing back and forth to hit bomber engines.  Damage list just before landing was fairly extensive, but the wings and tail stayed with me even through the belly landings.  I did notice it seems to have a tendency to want to stall if you try to go too suddenly into a nose low turn at speed, but corrected quickly and easily.

[Kaz]

I know someone has the real Wright field test somewhere...Mobilize the forces, let's start digging!

[Karnak]

Originally posted by StarOfAfrica2
Doesnt seem that bad in the durability dept. to me.  

Hmm.  So far it seems that any 20mm hit to the wing will remove the wing.

Maybe I'm getting unlucky.  I'd like to test it in a controled environment.

[Mitsu]

Pyro wrote:
>However, this theory fell apart when Busa's research found that
>the prototype's top speed of 624 kph was reached using
>+350mm/3000 RPM.

Question.

I've confirmed 4th prototype's top speed of 631kph was reached using +350mm/3000rpm from the books, but I couldn't find out 1st prototype is reached 624kph using +350mm/3000 RPM. Where did he get this source?

Thanks.

[leitwolf]

From a scenario (and possibly C'T) perspective, a better performing Ki84 would do a marvellous job to keep the P-XX and F-YY drivers honest. My little hint (and hope) is that once substantial data for the "fast Ki84" emerges, we get this plane as a new variant and retain the existing "early" Frank.
If the Ki84 model as of now is representative for an early -84, dont fix what is not broken.
I think both planes could complement each other very well.

[Oldman731]

Originally posted by leitwolf
From a scenario (and possibly C'T) perspective, a better performing Ki84 would do a marvellous job to keep the P-XX and F-YY drivers honest. My little hint (and hope) is that once substantial data for the "fast Ki84" emerges, we get this plane as a new variant and retain the existing "early" Frank.
If the Ki84 model as of now is representative for an early -84, dont fix what is not broken.
I think both planes could complement each other very well.

I agree.

- oldman